In the following text, various applications of the invention are described, with more specific reference to its preferred applications in the field of the food industry for candling eggs. The locations subjected to radiation examination in this case are, in practice, the various cells of the egg crate grid in which the eggs are arranged, each being held in one of the cells. In addition, the egg candling operations, as they are currently practiced at an intermediate stage in the production of chicks for chicken eggs, between an incubator and a hatching device, are intended to examine the eggs by transparency by submitting them individually to a light beam, usually of infrared light, in order to establish a distinction between the eggs based on the state of fertilization of each, and thus to allow selection of those that have been fertilized while excluding those that have not been fertilized, with the fertilized eggs being sent to the hatching devices where the chicks are born. Specifically, each egg is characterized as fertilized or non-fertilized according to the diminution in a light beam to which it is exposed. However, whether this is done for eggs, for any other type of product in individualized units, or even for discrete locations made up of adjacent zones of a contained product, it will obviously be possible for the professional to transpose the vocabulary to apply the invention to other criteria of discrimination and selection, as well as other industrial areas.
In conventional egg candling installations, including those described in particular in patent application WO 99/14589 (Ecmas) or in the American U.S. Pat. No. 5,900,929 (Embrex), the practice is to process the egg crate grids in series, each grid containing a batch of eggs. Generally, direct use is made of crate grids used for incubating eggs. Eggs are placed therein in cells arranged in locations at regular intervals, in each egg crate grid, following a repeated pattern of longitudinal lines and latitudinal rows. The grids are placed successively horizontally over a conveyor appliance (for instance, of the conveyor belt type that rotates in a closed circuit), which conveys them through the optoelectronic examination site.
In this site, a radiating source emits an incident light flow that illuminates each of the eggs individually. When dealing with an application aimed at locating the air chamber inside the eggs, these means of illumination for the eggs are arranged on the same side as the detectors that receive the light emerging from the eggs and determine its composition according to the modification caused by each of them. The same would be true if, for instance, the application consisted in examining the coloring of fruits that were individually maintained, instead of eggs, in the cells of similar crate grids. However, in the more common application, i.e. egg candling, aimed at distinguishing fertilized eggs from those that are to be removed from the particular series, as in our example here, the source is generally placed below the conveyor circuit of the crate grids, to produce illumination from below to above toward the detecting appliances located above. It is advantageous but not obligatory to use a light that lies within the range of the infrared wavelength.
For detection methods that are sensitive to the emerging flow, one can use either individual sensors that are associated with each egg respectively, or preferably a video camera. When the detected light intensity descends below a predetermined threshold, indicating an attenuation threshold that can be computed in known manner depending on the diffusion properties of the eggs or determined experimentally, indicating the presence of an embryonic germ, and the system is instructed to automatically designate the examined eggs as being fertilized. The cell structure of the incubation crate grids is naturally adapted to optical examination. In general, the cells are bottomless, for examination by transmission, and they maintain the eggs with the large vertical axis, which lends itself well to an examination that is advantageously produced in the vicinity of this large axis.
The locations in lines and rows, especially for the cells that receive eggs, are most commonly configured with square patterns, or triangular, or particularly hexagonal patterns, in the style known as quincunx. Quincunx arrangements differ from those in square patterns in that, from one row to the next, the cells are no longer aligned in the longitudinal moving direction, but are offset laterally. For instance, if the offset distance can be any fraction of the pace of distribution of the cells within each row, the most frequent quincunx arrangement corresponds to a displacement of a half-step in a regular distribution of the hexagonal type.
In addition, the means of illumination and the associated means of detection are arranged and controlled to match the spatial configuration of the cells of the crates. In industrial applications, an optimal compromise between cadence of the processing, reliability of the sorting, costs of installation and operation requires simultaneous operation on a group of locations of eggs in repetitive manner in the course of the passage through a visiometric examination point in which the material remains stable. This means that in general, the examination takes place row by row as the successive rows pass under the detectors. From this point of view, the invention foresees, as will be explained further hereafter, examination of the displaced rows of the quincunx arrangements by considering them grouped together in order to use the same means of illumination and means of detection, for instance on the even numbered row and the odd numbered row in each pair of rows of a hexagonal arrangement.
In a preferential manner, the analysis by visiometric analysis aimed at detecting the presence of fertilized eggs takes place at the entry to the egg-candling installation. The crates are placed manually or automatically on the conveyor device, for instance a conveyor on a rotating belt in closed circuit, which takes them through the visiometric examination site. On leaving said site, the installation is advantageously supplemented by a marking station, where the eggs are marked selectively so that they are transferred thereafter toward distinct reserved destinations, depending on whether they are fertilized or not. The sorting is generally carried out manually to eliminate from the chain the non-fertilized eggs, but it can also be performed automatically by a supplementary apparatus.
The invention aims to improve the conditions for industrial exploitation of such egg-candling installations, principally concerning the reliability of the detection of the state of fertilization of the eggs and the cadence of processing. Especially in the case of an installation in which the egg crates are treated linearly in a marking station after the visiometric examination station, the problem arises of being able to mark the eggs efficiently and rapidly by directly utilizing the signal produced by numerical processing of the images captured by the visiometric examination while taking care not to risk breaking the egg shells. In the same concern for processing at high cadence in full security in the selection of the eggs depending on their state of fertilization, it is useful to find a solution to difficulties that appear at the visiometric examination station where more than two conditions are to be distinguished for each location of the entire group that is passing through, especially if in some rows of eggs certain cells have remained empty accidentally.